Highlights
Citric acid increases induction time during precipitation of struvite-K.
Citric acid reduces the amount of precipitated struvite-K.
Precipitation of struvite-K is inhibited by formation of Mg citrate complexes.
Surface adsorption of citric acid affects size and shape of the struvite-K crystals.
Citric acid binds to (0 0 1) faces of growing struvite-K crystals.